There is a system including a content reproduction apparatus (such as a disc player) for reproducing content data (such as video data and audio data) recorded on a recording medium such as a digital versatile disc (DVD) and a Blu-ray Disc (BD) or downloaded via a network from a server or the like, and a content output apparatus (such as an amplifier) for receiving digital data reproduced and output by the content reproduction apparatus, amplifying audio data of the digital data, and outputting the audio data to a speaker, and outputting the audio data and video data to a display apparatus such as a monitor or a television set.
In recent years, in this system, a digital interface such as the Institute of Electrical and Electronic Engineers (IEEE) 1394 interface or the High-Definition Multimedia Interface (HDMI) is used for the transmission of the content data from the content reproduction apparatus to the content output apparatus, and the audio data and the video data reproduced by the content reproduction apparatus can be transmitted as high quality digital data to the content output apparatus.
In the system for transmitting the content data from the content reproduction apparatus to the content output apparatus by using the digital interface, a master clock generated by a clock generation part of the content output apparatus and a master clock generated by a clock generation part of the content reproduction apparatus are not synchronized with each other. Therefore, a jitter is generated in the content data (digital data) received from the content reproduction apparatus, and the content output apparatus thus cannot correctly demodulate the received digital data, and hence noise is generated on an audio signal output from a speaker, the audio signal is interrupted, or an image quality of the video signal degrades.
As a method of synchronizing the master clocks of the content reproduction apparatus and the content output apparatus with each other, Patent Literature 1 discloses a method (transmission apparatus clock control mode) involving generating, by the content output apparatus, a master clock synchronized with the audio data transmitted from the content reproduction apparatus, and demodulating the audio data transmitted from the reproduction apparatus by using the master clock.
Moreover, as another method, Patent Literature 2 discloses a method (reception apparatus clock control mode) involving detecting, by the content output apparatus, whether the master clock generated by the clock generation part and the digital data transmitted from the content reproduction apparatus are synchronized with each other or not, generating correction information for correcting a loss of the synchronization between the generated master clock and the audio data, and transmitting the correction information to the content reproduction apparatus. In this method, the content reproduction apparatus adjusts the frequency of the master clock based on the correction information received from the content output apparatus, encodes the audio data by using the adjusted master clock, and transmitting the encoded audio data to the content output apparatus.